Misr University for Science and Technology
Faculty of Engineering
Dep. of Communication and Electronics
Communication III
ECE543
Research topic:
Wi-Fi concept and foundation
Name: Abdelrahman Waleed
ID:81109
Supervised by: DR. Ashraf Samy
Introduction
The term Wi-Fi is short for "wireless fidelity". Wi-Fi is a family of
wireless network protocols based on the IEEE 802.11 family of
standards, which are commonly used for local area networking of
devices and Internet access, allowing nearby digital devices to
exchange data by radio waves. These are the most widely used
computer networks, used globally in home and small office networks
to link devices and to provide Internet access with wireless routers and
wireless access points in public places such as coffee shops, hotels,
libraries, and airports to provide visitors.
Wi-Fi's radio bands work best for line-of-sight use. Many common
obstructions such as walls, pillars, home appliances, etc. may greatly
reduce range, but this also helps minimize interference between
different networks in crowded environments.
Versions and generations
Equipment frequently supports multiple versions of Wi-Fi. To
communicate, devices must use a common Wi-Fi version. The
versions differ between the radio wavebands they operate on, the radio
bandwidth they occupy, the maximum data rates they can support and
other details.
Waveband consideration
The 802.11 standard provides several distinct radio frequency ranges
for use in Wi-Fi communications: 900 MHz, 2.4 GHz, 3.6 GHz, 4.9
GHz, 5 GHz, 5.9 GHz and 60 GHz bands. Each range is divided into
a multitude of channels. In the standards, channels are numbered at 5
MHz spacing within a band.
Countries apply their own regulations to the allowable channels,
allowed users and maximum power levels within these frequency
ranges. 802.11b/g/n can use the 2.4 GHz band, operating in the
United States
Transmitter power
Compared to cell phones and similar technology, Wi-Fi transmitters
are low-power devices. In general, the maximum amount of power
that a Wi-Fi device can transmit is limited by local regulations, such
as FCC Part 15 in the US. Equivalent isotropically radiated power
(EIRP) in the European Union is limited to 20 dBm
Antenna functionality
Higher gain rating (dBi) indicates further deviation (generally toward
the horizontal) from a theoretical, perfect isotropic radiator, and
therefore the antenna can project or accept a usable signal further in
particular directions.
On wireless routers with detachable antennas, it is possible to improve
range by fitting upgraded antennas that provide a higher gain in
particular directions. Outdoor ranges can be improved to many
kilometres (miles) through the use of high gain directional antennas
at the router and remote device(s).
Usage and functions
Wi-Fi technology may be used to provide local network and
Internet access to devices that are within Wi-Fi range of one or
more routers that are connected to the Internet. The coverage of
one or more interconnected access points can extend from an
area as small as a few rooms to as large as many square
kilometres
Wi-Fi provides services in private homes, businesses, as well as
in public spaces. Wi-Fi hotspots may be set up either free of
charge or commercially.
Wi-Fi positioning systems use the positions of Wi-Fi hotspots to
identify a device's location.
It's used when GPS isn't suitable due to issues like signal
interference or slow satellite acquisition.[68] This includes
assisted GPS, urban hotspot databases, and indoor positioning
systems.
References
https://watech.wa.gov/WiFi-definition-and-meaning
https://www.newscientist.com/question/what-does-wi-fi-
stand-for/
